Quote:
Originally Posted by David Sklansky
I'm surprised at you. I don't know what made him change his mind but if it was something along the lines of "I used to think that to have life we needed 500 things to be true each of which is a 99% shot. But now think they are 98% shots" that slight change would be more than enough to change an estimate from billions to zero.
I'll let Not Ready elaborate.
My impression from listening to a lot of RTB on why astronomers as opposed to biologists are beginning to doubt ETs is, that though we have only found planets relatively close to us, we know so much more about what requires the formation of planets and due to the uniformity that can be observed even to extreme distances, there is less and less reason to expect earth like planets - and much of it has to do with the unique properties of our sun, solar system, earth and moon. One comment Marcy made was on the very fine balance of water on earth - .02 percent of the earth's mass is water but water is the most prevalent molecule in the universe. And given what is required for the water cycle to work (techtonics, atmosphere, the moon-forming collision, etc.) on earth, that alone makes another planet like ours very unlikely. He also made a very interesting comment which I've thought about before - that so many organisms have existed for many millions of years, virtually unchanged, and show no signs of developing higher intelligence - dolphins, for instance. So I think he is changing his mind because of many different factors. He's not the only one who is, just he's fairly well known for being pro-ET and is a respected scientist who's done a 180 for non-religious reasons. I think Flew became a deist for much the same reasons, but he's just a high-falutin philosopher, so he doesn't count.